1. Field of the Invention
The present invention relates to an antiglare film, a polarizing plate having the subject antiglare film and an image display device.
2. Description of the Related Art
In various liquid crystal display devices such as a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD) and a cathode ray tube display device (CRT), an antiglare film having an antiglare hard coat layer laminated on a transparent plastic film substrate is disposed on the surface of a display for the purpose of preventing a lowering of contrast to be caused due to reflection of external light or reflection of an image by surface scattering.
In recent years, in liquid crystal televisions and so on, following a trend for prices to lower, image display devices having such an antiglare film mounted therein have widely diffused. Following this, an opportunity when the mounted antiglare film is exposed under various circumstances together with the image display device is increasing. In particular, such a liquid crystal television is handled in the same way as in a CRT having a glass-made surface, and as a result, danger that the surface of the liquid crystal display device is scared has increased. For that reason, the antiglare film which is disposed on the uppermost surface of the liquid crystal display device is being required to have high physical strength (for example, abrasion resistance, etc.) in addition to a high visibility improving effect which has hitherto been required.
In order to obtain high physical strength, there is proposed an antireflection film in which a hard coat layer having a film thickness of 10 μm or more is laminated on a cellulose acylate film by coating a curable composition containing a photocurable resin and an organic solvent thereon, drying and photocuring (see, JP-A-2003-227902).
Also, there is proposed an antiglare film having a high surface hardness, in which an antiglare layer having a film thickness of from 15 to 35 μm is laminated on a cellulose acylate film by coating a curable composition containing a resin particle having an average particle size of from 6 to 15 μm, a curable resin and an organic solvent thereon, drying and photocuring (see, JP-A-2007-041533).
Though the antiglare layer having an increased film thickness is effective for preventing a scar generated by a force which is applied vertically to the surface of a display screen, it was not effective against a scratch generated by a parallel force to the surface.
There is disclosed a method for applying a thin film containing a silica particle on a layer having fine recesses and projections on the surface thereof (see, JP-A-7-290652). However, according to this method, since the thin film layer contains a silica particle of 1 μm or more, there is a concern that surface scattering is strong so that when observed in a bright room, whitishness is strongly viewed.
There is disclosed an antiglare film in which a fine particle-containing curable resin layer containing an inorganic or organic fine particle and a fine particle-free clear curable resin layer are laminated in this order on a plastic film substrate (see, JP-A-10-325901). However, a further abrasion resistant effect of the surface was demanded.
Also, there is generally known an antiglare film in which an antiglare layer and a fluorine based binder-containing low refractive index layer are laminated in this order on a plastic film substrate (see, JP-A-11-305010). However, in general, the fluorine based binder is weak in cohesion, and therefore, in antiglare films having such a fluorine based binder layer laminated on the upper surface thereof, an improvement of the abrasion resistance was demanded.